Question

Choose from among the following cipher systems, from best to the worst, with respect to ease of decryption using frequency analysis.

(a) Random Polyalphabetic, Plaintext, Playfair

(b) Random Polyalphabetic, Playfair, Vignere

(c) Random Polyalphabetic, Vignere, Playfair, Plaintext

(d) Random Polyalphabetic, Plaintext, Beaufort, Playfair

This question was addressed to me in an interview.

This is a very interesting question from Substitution and Transposition Techniques in section Classical Encryption Techniques of Cryptograph & Network Security

Answer 1

Right option is (c) Random Polyalphabetic, Vignere, Playfair, Plaintext

Explanation: Random Polyalphabetic is the most resistant to frequency analysis, followed by Vignere, Playfair and then Plaintext.